If you can dictate terms for the match then no flying and no spells. And pretty much the only way to do that would be playing off the devil's pride. They are lawful creatures after all and might abide by such an agreement unless threatened with death. Something along the lines of "What need would such a mighty lord of darkness such as yourself have for those tactics against one as lowly as I? Enjoy the satisfaction of rending my mortal flesh with claws and crushing my puny frame with your tail. There is no need to take to the sky when you can relish swift victory on the ground. Your mighty magics would be a waste against me."
In a stand-up melee fight your main objective would be pushing your Fortitude save through the roof against that poison. I'd also suggest using Expertise and staying mobile to avoid a full attack, since that means you'd avoid the bite/poison altogether as well as the chance at getting grappled by the tail. The only way to do this, though, is to have a 10 ft. reach by trading your sword for a polearm or by using a spell to enlarge/polymorph/whatever. If you can't somehow develop a reach then your only option is to go toe to toe with it and that's a terrible idea.
Depending on the DM, s/he might try to trade out the claw attack for either the bite or tail if the Fiend is denied a full attack. The gloves will help you in grapple checks and I've already mentioned driving the Fort save as high as possible so the only fail would be a natural 1.
If you can negotiate a no magic melee battle and get yourself some reach then you have a chance in my opinion. Just stick and move, stick and move, stick and move. You can dump 9 off your BAB and add to AC while still having a 50% chance to hit the Fiend, which will in turn only have a 25% chance to hit you with any given attack. Granted, darting away after your swing will provoke an AoO but you're still a lot better off by my reckoning.
Random thought: how can you use your wand of charm monster? Or is it just for looks?
